Iron pallet, method of manufacturing the same, and intermediate support for the same

ABSTRACT

The present invention relates to an iron pallet which is essentially used to conveniently, quickly and correctly handle articles or products when producing, transporting and keeping the articles or products, a method of manufacturing the same, and an intermediate support for the same. A coating layer is formed on an upper surface of an iron pallet which will come into contact with a product to be placed on the iron pallet, by processing a solid material at a high temperature using plasma, arc or flame to produce fine particles and by momentarily jetting the fine particles to the upper surface of the iron pallet such that fine particles are formed on the upper surface of the iron pallet. Therefore, fine depressions and prominences are created to prevent slip of the product placed on the pallet, and excellent corrosion resistance is rendered when compared to a conventional iron pallet.

TECHNICAL FIELD

The present invention relates to an iron pallet which is essentiallyused to conveniently, quickly and correctly handle articles or productswhen producing, transporting and keeping the articles or products in anindustrial field or in a distribution procedure, a method ofmanufacturing the same, and an intermediate support for the same.

BACKGROUND ART

So far, a pallet generally used for transporting and keeping products ismanufactured by assembling timber having predetermined thickness orwidth in the shape of a lattice and driving fastening elements such asnails into the overlapped portions of the timber. The palletmanufactured in this way has a drawback in that it has a poor strengthand a short lifetime. Specifically, when the pallet is used as aplatform on which bricks, stones, etc. are stacked in the open air, thepallet is exposed to moisture or water. Therefore, moisture or water maysoak into the timber to cause deformation of the timber, and the timbermay be decomposed and gather mold, as a result of which an offensiveodor can be produced and damage to the articles placed on the pallet canbe caused. Further, when considering a situation that almost all of rawmaterials are imported, waste of foreign currency, unnecessaryconsumption of resources, environmental pollution may result.Accordingly, in order to cope with the problems related with thedecomposition and poor strength as disadvantages of the timber, a palletmade of synthetic resin (plastic) has been utilized.

However, while the pallet made of synthetic resin is suitable for massproduction, exhibits an excellent strength and has an extended lifetimewhen compared to the conventional wooden pallet, since the entire palletis integrally formed by injection molding, the pallet has a substantialweight. Due to this fact, disadvantages are caused in that loadingefficiency is degraded to serve as a cause for increasing a physicaldistribution cost, and it is difficult to recycle the pallet made ofsynthetic resin whereby environmental issues may be raised.

Recently, in order to solve these problems, a pallet made of iron hasbeen disclosed in the art. Nevertheless, since the iron pallet has anumber of parts, a manufacturing cost increases and the automated massproduction of the iron pallet is difficult. Also, after the iron palletis used for extended periods, since screws or bolts used for assemblingthe iron pallet may be easily loosened by vibration, inconvenience canbe caused while using the iron pallet, and the lifetime of the ironpallet can be shortened. Under these circumstances, while another ironpallet which is integrally formed including leg parts has been suggestedin the art, an excessive equipment cost is required, and variousproblems are caused to conduct a proper function as a pallet in relationwith weight, manufacturing cost and in-use convenience in use.

As an invention solving these problems, the present applicant has filedseveral patent applications, in an example of which a reinforcing holeis defined in an upper plate and leg members are coupled to the lowerpart of the upper plate. Notwithstanding, an iron pallet which hasimproved in-use convenience and a simple construction is still requiredin view of economic efficiency. In particular, needs exist for an ironpallet which can maintain an excellent strength and can be easilyassembled while being composed of an upper plate, a lower plate and anintermediate member as main component elements.

Meanwhile, the upper surface of an iron pallet which comes into contactwith products placed on the pallet is likely to be abraded or broken dueto exposure to corrosion and physical and chemical damages, and theproducts are apt to slip on the upper surface of the iron pallet. Asmethods for solving this problem, a pigment such as epoxy and paint issimply applied, or a galvanized iron sheet is used for forming the ironpallet. However, even in these methods, the problems related with theslip of the products and corrosion of the iron pallet are not thoroughlysolved, and the galvanized iron sheet has a drawback in that it isexpensive.

In the particular case of a pallet used for curing cement products,while a pallet made of stainless steel can be advantageously used,because the cost of the pallet made of stainless steel is expensive oversix to ten times the cost of a hot-rolled iron sheet, the pallet made ofstainless steel cannot be adequately used. In the case of the palletmade of the hot-rolled iron sheet which is relatively cheap, because itis used in a manner such that finished cement products are loaded on thepallet and the pallet is moved by a conveyor, a bogie or a forklift intoa steam curing room to cure the cement products under a hightemperature, the surface of the pallet made of the hot-rolled iron sheetis likely to be corroded. Particularly, the corner portions of thepallet are exposed to frequent contact with foreign objects, they arecorroded to an increased degree.

Moreover, a conventional iron pallet comprises an upper plate, a lowerplate and an intermediate plate. While these component elements areassembled with one another by means of screws, welding, riveting, etc.,the assembling operations are proved labor and cost intensive, technicaldifficulties are accompanied with, defects are caused while using thepallet in situ after manufacture. That is to say, while the assemblyusing the screws provides a firm structure, the structure is likely tobe adversely influenced by vibration, a labor cost is increased, and itis difficult to automatize the manufacturing procedure. In the case ofassembling the pallet by welding, difficulties may be caused dependingupon a working condition, and an initial equipment cost is excessivelyrequired when automatizing the manufacturing procedure. Even in theremaining method, satisfiable results cannot be obtained in terms ofcost and quality.

DISCLOSURE Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide an iron pallet which prevents slip of a productas occurred in the case of a conventional iron pallet, has excellentcorrosion resistance when compared to the conventional iron pallet, andis coated on its side surface and upper and lower edges with acorrosion-resistant and abrasion-resistant material when being used forcuring cement products, so that initial quality of the iron pallet canbe maintained for extended periods and the iron pallet can bemanufactured at a reasonable cost.

Another object of the present invention is to provide an iron palletwhich can be easily assembled while maintaining the strength of aconventional iron pallet as it is.

A further object of the present invention is to provide an iron palletwhich can be automatized in its manufacturing procedure to be quicklymanufactured, has a light weight, can be conveniently assembled, and canbe manufactured at a reasonable cost to accomplish competitiveness.

Yet another object of the present invention is to provide an iron palletwhich is constructed in consideration of the fact that an intermediatesupport must have strength capable of standing the weight of a productplaced on an upper plate and must be conveniently manufactured and thatupper and lower plates must be quickly assembled with each other withsufficient strength at connection regions, and which has an intermediatesupport having a structure capable of standing the weight of a productplaced on an upper plate and easily connecting upper and lower plates toeach other with excellent strength.

Technical Solution

The present invention is directed for an iron pallet (1) characterizedin that a coating layer (5) is formed on an upper surface of the ironpallet (1) which will come into contact with a product to be placed onthe iron pallet (1), by processing a solid material at a hightemperature using one of plasma, arc and flame to produce fine particles(6) and by momentarily jetting the fine particles (6) to the uppersurface of the iron pallet (1) such that fine particles (6) are formedon the upper surface of the iron pallet (1).

Also, since an iron pallet (7) for curing a cement product is used at ahigh temperature in a manner such that the produced cement product isloaded on the iron pallet (7) and the iron pallet (7) is moved into asteam curing room by a conveyor a bogie or a forklift to cure the cementproduct at the high temperature, the corner portions of the pallet (7)is likely to be severely corroded. In order to cope with this problem,the coating surface (8) of the iron patter (7) for curing a cementproduct is formed at the corner portions of the iron pallet (7) whichare most likely to be corroded. The coating surface (8) is formed on theiron pallet (7) to extend over a distance of no greater than 50 mm whenmeasured from respective edges of the iron pallet (7). The fineparticles (6) are mainly formed from one selected from a groupconsisting of zinc, stainless steel, alloy of zinc and aluminum, andalloy of zinc and stainless steel. Alternatively, the fine particles (6)are formed from a mixture of stone, sand and iron powder, or variousceramic particles.

Further, the present invention is directed for a method for forming acoating surface (5, 8) on an iron pallet (1, 7), comprising the steps offorming a material such as metal, nonmetal and ceramic into wire orpowder using one of plasma, arc and flame; melting and momentarilyjetting the wire or fine particles (6) comprising the powder to asurface of the iron pallet (1, 7) using a thermal sprayer; and sealingthe surface of the iron pallet (1, 7) to which the wire or fineparticles are jetted, by applying liquid phase thermosetting resin suchas epoxy resin, urethane resin and lacquer resin on the surface of theiron pallet (1, 7) using a sprayer, a brush or a roll.

Also, the present invention is directed for a method for forming acoating surface (5, 8) on an iron pallet (1, 7), comprising the steps offorming a material such as metal, nonmetal and ceramic into wire orpowder using one of plasma, arc and flame; melting and momentarilyjetting the wire or fine particles (6) comprising the powder to asurface of an iron plate using a thermal sprayer; sealing the surface ofthe iron plate to which the wire or fine particles are jetted, byapplying liquid phase thermosetting resin such as epoxy resin, urethaneresin and lacquer resin on the surface of the iron plate using asprayer, a brush or a roll; and cutting the iron plate having undergonethe jetting and sealing steps and fabricating a pallet (1, 7).

The present invention is illustrated in FIGS. 1( a) and 1(b), and 2(a)and 2(b). FIGS. 1( a) and 2(a) illustrate the iron pallet (1) and theiron pallet (7) for curing a cement product, respectively, which areentirely coated on their surfaces, and FIGS. 1( b) and 2(b) illustratethe iron pallet (1) and the iron pallet (7) for curing a cement product,respectively, which are partially coated on their surfaces.

The present invention is directed for an iron pallet (21) comprising anupper plate (22), a lower plate (23) and an intermediate member (24),wherein the intermediate member (24) has a substantially U-shapedcross-section, concaved reinforcing portions (29) are formed onrespective walls of the intermediate member (24), and lockingprojections (28) for locking the upper plate (22) and the lower plate(23) are formed on upper and lower ends of the intermediate member (24)on which the concaved reinforcing portions (29) are not formed. Thepresent invention is further directed for the iron pallet (21) whereineach locking projection (28) is divided into two parts which are bent inopposite directions.

The present invention will be described below in detail with referenceto the accompanying drawings. FIG. 3 is a perspective view of the ironpallet (21) formed with the locking projections (28) according to thepresent invention, FIG. 4 is a detailed view of the intermediate member(24) of the iron pallet (21) shown in FIG. 3, and FIG. 5 is a detailedview of another embodiment of the intermediate member (24) of the ironpallet (21) shown in FIG. 3. At this time, it is advantageous in thelight of easy locking of the upper and lower plates (22 and 23) that thelocking projections (28) are formed to have a semi-circular sectionalshape.

By constructing the present invention as described above, due to theconfiguration of the U-shaped cross-section of the intermediate member(24) and by the interaction of the concaved reinforcing portions (29)and the locking projections (28), an assembly type iron pallet (21)which has excellent strength and locking force can be manufactured.

A direction which the locking projections 28 face may be freely changedas occasion demands, and locking grooves which respectively correspondto the locking projections (28) are defined in the upper plate (22) andthe lower plate (23) so that the upper and lower parts are symmetricallystructured.

By forming the intermediate member (24) to have the U-shapedcross-section in the present invention, it is possible to effectivelysupport the load applied downwards, and due to the presence of theconcaved reinforcing portions (29), support strength can be furtherimproved. By the locking projections (28), leftward and rightwardvibration can be minimized.

The present invention is directed for an iron pallet (41) which has apress joint part. The present invention provides an iron pallet (41)comprising an upper plate (42) and a lower plate (43), wherein, afterone end of the upper plate (42) is overlapped with the lower plate (43),a punch (12) serving as an upper mold is pressed into a through-hole ofa lower mold (13) by a press, whereby a press joint part (45) having ahole (44) is formed between the upper and lower plates (42 and 43).

Also, the present invention is directed for an iron pallet (41) whichhas a press joint part. In this iron pallet (41), a push pin (15) and asupport spring (16) are installed below the lower mold (13), such that,after the punch (12) is introduced into the lower mold (13) andsimultaneously perforates the upper and lower plates (42 and 43), tornportions of the upper and lower plates (42 and 43) are further bentoutward by the push pin (15) biased by returning force of the spring(16).

Further, the present invention is directed for an iron pallet (41) whichhas a press joint part. In this iron pallet (41), an intermediate plateis intervened between the upper and lower plates (42 and 43), and thepunch (12) serving as the upper mold is pressed into the through-hole ofthe lower mold (13) by the press, whereby press joint parts (45) arerespectively formed between the upper plate (42) and the intermediateplate and between the intermediate plate and the lower plate (43).

The present invention is directed for an iron pallet (41) which has apress joint part. In this iron pallet (41), the lower mold (13) isconstructed to be moved in a radial direction, and an annular spring(19) circumferentially surrounds the lower mold (13), such that thelower mold (13) can be moved radially outward when the punch (12) islowered and can be moved radially inward to be returned to its originalshape when the punch (12) is raised.

Moreover, the present invention is directed for an iron pallet (41)comprising an upper plate (42) and a lower plate (43), wherein, afterone end of the upper plate (42) is overlapped with the lower plate (43),a punch (12) serving as an upper mold is pressed by a press into aconcaved part of a lower mold (13) which is defined by a plurality ofsplit movable dies assembled with one another, whereby a press jointpart (46) is formed between the upper and lower plates (42 and 43), andwherein the lower mold (13) is constructed to be moved in a radialdirection, and an annular spring (19) circumferentially surrounds thelower mold (13), such that the lower mold (13) can be moved radiallyoutward when the punch (12) is lowered and can be moved radially inwardto be returned to its original shape when the punch (12) is raised,whereby the press joint part (46) is bent outward while it is notperforated but undergoes drawing.

Specifically, the press joint part (46) is formed to have aconfiguration of a circle, a rectangle or a polygon.

The present invention is illustrated in FIGS. 6 through 11.

The present invention is directed for an iron pallet (61) characterizedin that a surface of the iron pallet (61) is coated with a coatingmaterial, and the coating material is one selected from a groupconsisting of a yellow ocher constituent, a bentonite constituent, azeolite constituent, a bioceramic constituent and a nano-sized silverconstituent.

In particular, as shown in FIG. 12, the present invention is directedfor an iron pallet (61) which is coated with a coating material andcomprises a box-shaped pallet (65).

While the suitable grain size of yellow ocher constituent used in thepresent invention is 1,000˜3,000 meshes, the iron pallet can bemanufactured by adding in yellow ocher constituent of various grainsizes as occasion demands.

Also, zeolite and bentonite each having a grain size of 1,000˜3,000meshes are used to manufacture the iron pallet.

Further, the iron pallet (61) can be manufactured by adding in jade,germanium, elvan, bioceramic particles as ceramic beneficial to thehuman body, etc. or by adding in nano-sized silver particles.

By coating the above-described yellow ocher constituent, bentoniteconstituent, zeolite constituent, bioceramic constituent, nano-sizedsilver constituent, etc. to the surface of the iron pallet, the ironpallet (61) according to the present invention which has undergone acoating process is manufactured. Here, the iron pallet (61) ismanufactured to have a box-shaped configuration so that fruits oragricultural products can be stored in a low temperature warehouse whilebeing placed on the iron pallet (61).

That is to say, it can be contemplated that a pallet can be integrallyformed on the lower end of a box-shaped storing case as in theconventional art so as to allow the fork of a forklift to be insertedthrough the lower end of the box-shaped storing case.

Therefore, by storing fruits, etc. in the box-shaped iron pallet (65)according to the present invention which has undergone a coatingprocess, excellent storing effect can be accomplished due to anions andfar infrared rays emitted from a coated portion (66).

Also, the present invention is directed for a lower plate structure ofan iron pallet. The iron pallet is characterized in that a lower plate(63) is installed under an upper plate, a locking lip (64) which projectupward and then is bent is formed at one side end of the lower plate(63), and the upper plate is fitted and locked into a space delimited bythe locking lip (64).

The present invention will be described below with reference to theaccompanying drawings.

FIG. 13 is a perspective view illustrating a lower plate (63) of an ironpallet which is formed with a locking lip (64) according to the presentinvention, FIG. 14 is a perspective view illustrating the lower plate(63) shown in FIG. 13, in which an end portion of the locking lip (64)is folded, and FIG. 15 is a perspective view illustrating the lowerplate (63) shown in FIG. 13, in which an end portion of the locking lip(64) is not folded.

An iron pallet is used in a manner such that it can be moved by aforklift, etc. while a product is loaded on the iron pallet. Since theiron pallet is moved along with the product, it should have a lightweight in consideration of a distribution cost, etc., and above all, itmust be manufactured so that labor and material costs are saved. Fromthis viewpoint, in the present invention, the locking lip (64) whichproject upward and then is bent is formed at one side end of the lowerplate (63) in a cutting and forming step so that the upper plate can befitted and locked into the space delimited by the locking lip (64),thereby obviating the need for screws, and bolts and nuts, as mechanicallocking elements, or a welding process.

Preferably, the locking lip (64) is formed to have a U-shapedcross-section such that the upper plate which comprises a flat plate canbe fitted into the locking lip (64) to allow the upper plate to betightly coupled to the lower plate (63).

In the present invention, the lower plate (63) is formed to have asquare wave-shaped cross-section in which prominences and depressionsare alternately defined so that strength of the lower plate (63) can beincreased. Hence, when forming the lower plate (63) using a formingmachine to have the square wave-shaped cross-section, the locking lip(64) is also bent.

Further, when occasion demands, the end portion of the locking lip (64)can be folded as shown in FIG. 14 to increase strength and prevent aworker from being injured by the sharp edge of the locking lip (64).

In addition, the present invention is directed for an intermediatesupport (80) for an iron pallet. The intermediate support (80)intervened between and locked to upper and lower plates (81 and 82) ofan iron pallet to support the upper and lower plates (81 and 82) ischaracterized in that the intermediate support (80) includes a frontwall (83) which is formed with a concaved portion (86) and side walls(84) which are bent from both side ends of the front wall (83) and areformed with concaved portions (86), so that the intermediate support(80) has a substantially U-shaped cross-section, and the upper and lowerends of the front wall (83) and the side walls (84) are bent inward, sothat the upper and lower plates (81 and 82) can be coupled to theintermediate support (80) over wide areas.

The coupling between the intermediate support (80) and the upper plate(81) and between the intermediate support (80) and the lower plate (82)is affected by welding.

Also, the intermediate support (80) is characterized in that theintermediate support (80) is formed by cutting a thin iron plate,bending both side portions of the cut thin iron plate to define asubstantially U-shaped cross-section and bending inward both upper andlower end portions of the cut thin iron plate so that the upper andlower plates (81 and 82) can be coupled to the intermediate support (80)over surface areas which are more wide than the other portions of theintermediate support (80).

The present invention is illustrated in FIGS. 16 through 18.

While the intermediate support (80) installed between the upper plate(81) and the lower plate (82) of the iron pallet must be manufactured tohave a simple construction so that the iron pallet has a light weight,the intermediate support (80) should have substantial strength. Also,the upper and lower plates (81 and 82) and the intermediate support (80)must be able to be quickly and firmly coupled with each other.

In the present invention, the upper and lower plates (81 and 82) and theintermediate support (80) are coupled with each other by welding,preferably, by spot welding. Therefore, the coupling region of theintermediate support (80) where the upper and lower plates (81) and (82)are coupled with the intermediate support (80) is formed to have anincreased surface area. To this end, the upper and lower ends of thefront wall (83) and both side walls (84) of the intermediate support(80) are bent inward at a right angle as shown in FIG. 16, and then, thebent portions (85) of the intermediate support (80) and the upper andlower plates (81 and 82) are coupled to each other by welding.

As in a conventional structure, in the intermediate support (80) of theiron pallet according to the present invention, the front wall (83) andthe side walls (84) are formed with the concaved portions (86) to bereinforced in their strength. One or more concaved portions (86) can beformed, and it is appropriate that the upper and lower plates (81 and82) and the intermediate support (80) are coupled to each other on fourpoints. Several intermediate supports (80) can be installed between theupper and lower plates (81 and 82) depending upon the weight of aproduct to be placed on the upper plate (81). The upper and lower plates(81 and 82) and the intermediate support (80) are formed of an ironplate. Further, in another embodiment of the present invention, theupper and lower plates (81 and 82) and the intermediate support (80) canbe coupled to each other by means of bolts and nuts, etc. rather than bywelding so that they can be disassembled from each other.

ADVANTAGEOUS EFFECTS

As described above, in the present invention, since fine particles areformed on the surface of a pallet, fine depressions and prominences arecreated to prevent slip of a product placed on the pallet, and it ispossible to maintain excellent corrosion resistance when compared to aconventional iron pallet.

Also, in the present invention, because locking projections areprojectedly formed to lock upper and lower plates, an assemblingprocedure can be easily implemented while maintaining the strength ofthe iron pallet as it is.

Further, in the present invention which is directed for an iron palletassembled by pressing, the manufacturing procedure of the iron palletcan be automatized so that it is possible quickly manufacture the ironpallet, the iron pallet can have a light weight, and can be convenientlyassembled to reduce a manufacturing cost.

Moreover, in the present invention, the surface of the iron palletundergoes a coating treatment. A coating material includes one of ayellow ocher constituent, a bentonite constituent, a zeoliteconstituent, a bioceramic constituent and a nano-sized silverconstituent. Due to this fact, since anions and far-infrared rays aregenerated and emitted on and from the surface of the pallet and it ispossible to sterilize microorganisms, excellent effects can be obtainedwhen using the pallet to keep agricultural products in a place.

Furthermore, an intermediate support for the pallet according to thepresent invention can sufficiently stand the weight of the productsplaced on an upper plate, and since the intermediate support has anincreased surface area at a connection region where upper and lowerplates are connected with each other and is welded to the upper andlower plates, the coupling operation can be quickly conducted with theconnection region having excellent strength.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an iron pallet for transporting andkeeping articles or products according to the present invention;

FIG. 2 is a perspective view illustrating an iron pallet for curing acement product, on a surface of which a coating layer is formed;

FIG. 3 is a perspective view of an iron pallet formed with lockingprojections according to the present invention;

FIG. 4 is a detailed view of an intermediate member of the iron palletshown in FIG. 3;

FIG. 5 is a detailed view of another embodiment of the intermediatemember of the iron pallet shown in FIG. 3;

FIG. 6 is a perspective view of a pallet conventionally manufacturedusing screws;

FIG. 7 is a detailed view of an upper punch and a lower mold formanufacturing an iron pallet by performing pressing work according tothe present invention;

FIG. 8 is a detailed view of a press joint part formed after performingpressing work as shown in FIG. 7;

FIG. 9 illustrates a workflow for forming a press joint part having nohole on an iron pallet by performing pressing work as shown in FIG. 7;

FIG. 10 illustrates press joint parts formed on an iron pallet byperforming pressing work as shown in FIG. 7 and having no hole;

FIG. 11 is a plan view illustrating a state in which an annular springis installed around a lower mold when performing pressing work as shownin FIG. 7;

FIG. 12 is a perspective view of a box-shaped iron pallet havingundergone a coating process according to the present invention;

FIG. 13 is a perspective view illustrating a lower plate of an ironpallet which is formed with a locking lip according to the presentinvention;

FIG. 14 is a perspective view illustrating the lower plate shown in FIG.13, in which an end portion of the locking lip is folded;

FIG. 15 is a perspective view illustrating the lower plate shown in FIG.13, in which an end portion of the locking lip is not folded;

FIG. 16 is a detailed view of an intermediate support for an iron palletaccording to the present invention;

FIG. 17 is an assembled view of an upper plate, a lower plate and anintermediate support according to the present invention which are shownin FIG. 16; and

FIG. 18 is a detailed view illustrating a state in which the upperplate, the lower plate and the intermediate support shown in FIG. 16 areassembled with one another.

BEST MODE

Embodiments of an iron pallet according to the present invention whichis specially treated and has a corrosion and abrasion resistance will beconcretely described below.

In a conventional method for painting a galvanized iron plate, zinc tobe applied as an aqueous solution and paint are mixed with each other.However, in a novel method according to the present invention, a solidmaterial is processed at a high temperature into the shape of fineparticles, and the fine particles are momentarily attached to thesurface of a metal plate.

Concretely describing this new surface treatment method, a material suchas metal, nonmetal and ceramic is formed into wire or powder usingplasma, arc or flame, and the wire or fine particles comprising thepowder are melted and momentarily attached to the surface of an objectat a high temperature using a thermal sprayer. Preferably, after shotblasting is implemented for the surface of the object, thermal sprayingtreatment is implemented. In this case, corrosion resistance maintainingperiods for specified materials are as described below.

{circle around (1)} Corrosion resistance is maintained for about sixyears when plating melted zinc.

{circle around (2)} Corrosion resistance is maintained for about thirtyyears when thermally spraying alloy of zinc and aluminum.

In the case of using stone, sand and metal powder, advantageous effectsare obtained in that a material cost can be saved and abrasionresistance can be improved.

Generally, if zinc is plated on an iron plate with an aim of improvingcorrosion resistance, a product can slip on the iron plate. However, inthe present invention, due to the fact that fine particles (grains) ofmetal or nonmetal are formed on the surface of the iron plate byimplementing a thermal spraying operation, or a material in which stone,sand and metal powder are mixed with one another is coated on thesurface of the iron plate, slip of the product is prevented, andcorrosion resistance is improved.

Here, plasma means vapor which is divided at a high temperature intoelectrons having negative charges and ions having positive charges. Thatis to say, the plasma means vapor which has a considerably high chargeseparation degree and contains an approximately same number of negativecharges and positive charges to become neutral. When a temperature isgradually increased, almost all substances are converted from a solidstate via a liquid state into a vapor state. At several tens ofthousands ° C., a vapor is divided into electrons and an atomic nucleusto be converted into a plasma state.

The plasma has a very high temperature when observed from a thermalpoint of view, is conductive when observed from an electrical point ofview, allows a great current to pass through it, generates greatelectromagnetic force, emits light by itself, and contains therein agreat amount radicals or ions which are very active when observed from achemical point of view. Recently, the plasma has been widely used forproduction of energy, compounding and shaping of advanced materials,environmental processing, manufacture of information and communicationdevices, and so forth.

Describing the plasma used in the present invention, an arc which exitsa negative electrode flows to the outside through a hole defined in apositive electrode. At this time, gas flows along the inner wall of acontainer and around the arc. Due to the presence of this gas flow, theouter wall of the arc is cooled to decrease heat loss in a sidewarddirection, and the electric conductivity of the outer part of the plasmais decreased so that a current can be concentrated further to the centerpart of the plasma.

The temperature at the center part of the plasma reaches about 20,000°C., and therefore, it is possible to process a metal using plasma.Metals having high melting points, for example, such as tungsten,molybdenum, carbon, and so on, which cannot be welded or cut using gasflame in the conventional art, can be processed using the plasma. Thatis to say, plasma welding and plasma cutting belong to materialprocessing at a high temperature. Plasma spraying as a method in which ahigh melting point metal is melted by plasma and is coated on thesurface of a solid object to improve temperature resistance, corrosionresistance, abrasion resistance, etc. is used in the present invention.A gas stabilizing arc plasma torch which is currently used has severaltens of mega watts of output capacity and can generate plasma throughthermal ionization of an inert gas or a gas having high chemicalreactivity. The generated plasma may have a temperature of up to20,000K. A method for spraying a metal using arc or gas flame is alsoused in the same manner in the present invention. As an embodiment, amethod for thermally spraying a material on a raw metal before a palletis completely manufactured will be described below.

Described processes of the present invention, after a raw iron materialhaving the shape of a coil is slit, a small-sized skelp is paid out andthe surface of the skelp is heated. After the skelp is heated, foreignmaterials are removed from the surface of the skelp using shots or asteel brush, and an appropriate material is thermally sprayed onto thesurface of the skelp. In the next step, the sprayed portion of the skelpis sealed by applying liquid phase thermosetting resin such as epoxyresin, urethane resin and lacquer resin on the upper and lower surfacesof the skelp using a sprayer, a brush or a roll. Then, the resultantskelp is heated at a temperature of 130˜200° C. This heating step can beomitted as the case may be. Thereupon, a semi-product is wounded againinto the shape of a coil and then is formed by a forming machine. Then,this semi-product is mounted to a un-coiler, undergoes a roll formingprocess, is cut and is assembled to complete a pallet.

As another embodiment, a method for thermally spraying a material aftera pallet is prepared will be described below. First, after a large-sizedcold-rolled coil is slit, the slit coil is formed by a forming machine,is mounted to a un-coiler, and then undergoes a roll forming process.Then, the resultant coil is cut, and is assembled to complete a pallet.The completed pallet is heated to a temperature of 130˜200° C., andforeign materials are removed from the surface of the heated palletusing shots or a steel brush. Next, an appropriate material is thermallysprayed onto the surface of the pallet, and the sprayed portion of thepallet is sealed by applying liquid phase thermosetting resin such asepoxy resin, urethane resin and lacquer resin on the upper and lowersurfaces of the pallet using a sprayer, a brush or a roll. Then, thepallet having undergone the sealing process is heated. This heating stepcan be omitted as the case may be. Through the above-describedprocesses, a surface-treated iron pallet is completed. Whileconventional thermal spraying is implemented without pre-heating anobject, in the present invention, the thermal spraying is implementedafter pre-heating an object to a predetermined temperature.

Also, while the conventional sealing process is implemented withoutpre-heating an object, the present invention is particularlydistinguished from the conventional art in that, after pre-heating andsealing of the coating layer, a re-heating process (while it can beomitted as the case may be) is implemented, whereby a sealing process isnot simply implemented, but the surface coating layer is furtherreinforced. Above all, in the present invention, the sealing process isimplemented to close air holes possibly existing on the surface forwhich the thermal spraying is implemented, and one coating layer isfurther formed after implementing the thermal spraying process forreinforcing the surface of the pallet. Therefore, the present inventionis characterized in that two coating layers are formed on the surface ofthe pallet.

The coating surface is formed on the corner portions of the pallet onwhich corrosion is most likely to occur, and it is proper to form thecoating surface over a distance of 50 mm when measured from respectiveedges of the iron pallet.

The present invention directed for an iron pallet which is manufacturedthrough pressing will be described by an embodiment.

First, describing a method for manufacturing a pallet through pressingwith reference to FIG. 7, in the present invention, an iron plate havinga thickness of 0.6 mm is generally used. An upper plate 42 and a lowerplate 43 are overlapped with each other and are placed between a punch12 serving as an upper mold and a lower mold 13. In this state, thepunch 12 is moved downward. When the punch 12 is moved downward by apredetermined distance, the upper and lower plates 42 and 43 aresimultaneously perforated, and a hole 44 is defined. Then, as the punch12 is raised again, a push pin 15 is raised by the force of a spring 16to outwardly bent the torn portion of the upper plate 42 which definesthe hole 44.

The outward bending of the torn portion of the upper plate 42 whichdefines the hole 44 is effected due to configurations of the roundedportion of the punch 12, the rounded portion of a fixed die 17 of thelower mold 13, and the rounded portion of the push pin 15. In order toensure precise working, it is preferred that the rounded portion of thecorner portion of the push pin 15 have a roundness of about 1.5 R, andthe rounded portions of the corner portions of the punch 12 and thefixed die 17 have a roundness of about 1 R. When the push pin 15 israised and lowered in correspondence with the operation of the punch 12,the movement of the push pin 15 is limited by a holder 18. This fact canbe clearly understood from the drawing. It is appropriate that theupward and downward moving distance of the punch 12 and the push pin 15serving as a moving die 20 is about 4 mm. When considering the fact thatthe push pin 15 projects by about 2 mm from the horizontal surface ofthe fixed die 17 when measured before working processes are started andthe upward and downward moving distance of the push pin 15 is about 4mm, the maximum lowered position of the push pin 15 corresponds to 2 mmbelow the horizontal surface of the fixed die 17. The pressed joint partformed as the final resultant product completed through these processesis shown in FIG. 8.

Another embodiment of an iron pallet which is manufactured throughpressing according to the present invention will be described withreference to FIG. 9.

An upper plate 42 and a lower plate 43 are overlapped with each otherand are placed between a punch 12 serving as an upper mold and a lowermold 13. In this state, as the punch 12 is moved downward, materialsstart to be drawn. Then, the materials are expanded outward to be joinedwith each other. Of course, this occurs due to the fact that an annularspring 19 surrounds the circumference of split molds so that the moldsare moved radially outward when the punch 12 is lowered and are movedradially inward to be returned to their original positions when thepunch 12 is raised.

If the punch 12 is raised, the split movable dies 20 repeat operation ofreturning to their original positions by the annular spring 19. If thethickness of the iron plate is substantial, the diameter of the punch 12is decreased, and if the thickness of the iron plate is not substantial,the diameter of the punch 12 is increased.

FIG. 11 shows a state in which the movable die 20 of the lower mold 13is divided into four split dies. The split movable dies 20 are assembledto form an annular configuration, and a concaved portion is defined onthe lower surface of the split movable dies 20. The annular spring 19 isfixedly installed around the split movable dies 20 to fixedly hold thesplit movable dies 20. Therefore, the split movable dies 20 can befreely moved radially outward from the center point to be increased intheir radius or can be freely moved radially inward toward the centerpoint to be decreased in their radius. As occasion demands, the numberof the split movable dies 20 of the lower mold 13 can be adjusted.

INDUSTRIAL APPLICABILITY

As is apparent from the above descriptions, the present inventionprovides an iron pallet which is convenient to use and has a simpleconstruction. More particularly, the present invention provides an ironpallet which comprises an upper plate, a lower plate and an intermediatemember and which can be easily assembled while maintaining sufficientstrength.

Also, in the present invention, since fine particles are formed on thesurface of a pallet, fine depressions and prominences are created toprevent slip of a product placed on the pallet, and it is possible tomaintain excellent corrosion resistance when compared to a conventionaliron pallet.

Further, in the present invention which is directed for an iron palletassembled by pressing, the manufacturing procedure of the iron palletcan be automatized so that it is possible quickly manufacture the ironpallet, the iron pallet can have a light weight, and can be convenientlyassembled to reduce a manufacturing cost and improve economicefficiency.

1. An iron pallet characterized in that a coating layer is formed on anupper surface of the iron pallet which will come into contact with aproduct to be placed on the iron pallet, by processing a solid materialat a high temperature using one of plasma, arc and flame to produce fineparticles and by momentarily jetting the fine particles to the uppersurface of the iron pallet such that fine particles are formed on theupper surface of the iron pallet.
 2. The iron pallet according to claim1, wherein the coating surface is formed over a distance of 50 mm whenmeasured from respective edges of the iron pallet.
 3. The iron palletaccording to claim 1, wherein the fine particles are formed from oneselected from a group consisting of zinc, stainless steel, alloy of zincand aluminum, and alloy of zinc and stainless steel.
 4. The iron palletaccording to claim 1, wherein the fine particles comprise a mixture ofstone, sand and iron powder.
 5. A method for manufacturing an ironpallet, comprising the steps of: forming a material such as metal,nonmetal and ceramic into wire or powder using one of plasma, arc andflame; melting and momentarily jetting the wire or fine particles havingthe shape of the powder to a surface of the iron pallet using a thermalsprayer; and sealing the surface of the iron pallet to which the wire orfine particles are jetted, by applying liquid phase thermosetting resinsuch as epoxy resin, urethane resin and lacquer resin on the surface ofthe iron pallet using a sprayer, a brush or a roll.
 6. A method formanufacturing an iron pallet, comprising the steps of: forming amaterial such as metal, nonmetal and ceramic into wire or powder usingone of plasma, arc and flame; melting and momentarily jetting the wireor fine particles having the shape of the powder to a surface of an ironplate using a thermal sprayer; sealing the surface of the iron plate towhich the wire or fine particles are jetted, by applying liquid phasethermosetting resin such as epoxy resin, urethane resin and lacquerresin on the surface of the iron plate using a sprayer, a brush or aroll; and cutting the iron plate having undergone the jetting andsealing steps and fabricating a pallet.
 7. An iron pallet comprising anupper plate, a lower plate and an intermediate member, wherein theintermediate member has a substantially U-shaped cross-section, concavedreinforcing portions are formed on respective walls of the intermediatemember, and locking projections for locking the upper and lower platesare formed on upper and lower ends of the intermediate member on whichthe concaved reinforcing portions are not formed.
 8. The iron palletaccording to claim 7, wherein each locking projection is divided intotwo parts which are bent in opposite directions.
 9. An iron palletcomprising an upper plate and a lower plate, wherein, after one end ofthe upper plate is overlapped with the lower plate, a punch serving asan upper mold is pressed into a through-hole of a lower mold by a press,whereby a press joint part having a hole is formed between the upper andlower plates.
 10. The iron pallet according to claim 9, wherein a pushpin and a support spring are installed below the lower mold, such that,after the punch is introduced into the lower mold and simultaneouslyperforates the upper and lower plates, hole-defining portions of theupper and lower plates are further bent outward by the push pin biasedby returning force of the spring.
 11. The iron pallet according to claim9, wherein an intermediate plate is intervened between the upper andlower plates, and the punch serving as the upper mold is pressed intothe through-hole of the lower mold by the press, whereby press jointparts are respectively formed between the upper and intermediate platesand between the intermediate and lower plates.
 12. The iron palletaccording to any one of claims 9 to 11, wherein the lower mold isconstructed to be moved in a radial direction, and an annular springcircumferentially surrounds the lower mold, such that the lower mold canbe moved radially outward when the punch is lowered and can be movedradially inward to be returned to its original shape when the punch israised.
 13. An iron pallet comprising an upper plate and a lower plate,wherein, after one end of the upper plate is overlapped with the lowerplate, a punch serving as an upper mold is pressed by a press into aconcaved part of a lower mold which is defined by a plurality of splitmovable dies assembled with one another, whereby a press joint part isformed between the upper and lower plates such that the press joint partis not perforated but undergoes drawing.
 14. The iron pallet accordingto claim 13, wherein an intermediate plate is intervened between theupper and lower plates, and the press joint part is formed integrallywith the upper plate, the intermediate plate and the lower plate by thepunch serving as the upper mold and the lower mold.
 15. The iron palletaccording to claim 13 or 14, wherein the press joint part has aconfiguration of a circle, a rectangle or a polygon.
 16. An iron palletcharacterized in that a surface of the pallet is coated with a coatingmaterial, and the coating material is one selected from a groupconsisting of a yellow ocher constituent, a bentonite constituent, azeolite constituent, a bioceramic constituent and a nano-sized silverconstituent.
 17. The iron pallet according to claim 16, wherein thepallet has a box-shaped configuration.
 18. An iron pallet characterizedin that a lower plate is installed under an upper plate, a locking lipwhich project upward and then is bent is formed at one side end of thelower plate, and the upper plate is fitted and locked into a spacedelimited by the locking lip.
 19. An intermediate support intervenedbetween and locked to upper and lower plates of an iron pallet tosupport the upper and lower plates, characterized in that theintermediate support includes a front wall which is formed with aconcaved portion and side walls which are bent from both side ends ofthe front wall and are formed with concaved portions, so that theintermediate support has a substantially U-shaped cross-section, and theupper and lower ends of the front wall and the side walls are bentinward, so that the upper and lower plates can be coupled to theintermediate support over wide areas.
 20. The intermediate supportaccording to claim 19, wherein the upper and lower plates are coupled tothe intermediate support by welding.
 21. The intermediate supportaccording to claim 19, wherein the intermediate support is formed bycutting a thin iron plate, bending both side portions of the cut thiniron plate to define a substantially U-shaped cross-section and bendinginward both upper and lower end portions of the cut thin iron plate sothat the upper and lower plates can be coupled to the intermediatesupport over surface areas which are more wide than the other portionsof the intermediate support.